Long-term goals are: to understand effects of ultrafine (less than 0.1 microm) combustion aerosols and their reaction products with S02 on the lung, to characterize them and to understand processes leading to their formation during coal combustion. All aerosols are made in furnaces usable as feed-systems for animal exposure chambers. Exposures include: Zn0 alone with and with S02, Cu0 alone and with S02, coal combustion products generated from burning of characterized coals under controlled combustion conditions, and ultrafine aerosols of silica having a surface layer of Zn0 alone and with S02. Mixed exposures are to 1 PPM S02 and 1-5 mg/m3 metal oxide. Guinea pigs are exposed for 1 hr, 3 hr, 3 hr/day for 6 days, or 3 hr/day, 5 days/wk for 3 wks. Effects are evaluated at 1, 24, 48, 72 hrs post-exposure and, for the chronic studies, on alternate days up to 10 days after exposure. Functional change during exposure is evaluated by measurement of respiratory mechanics. Pulmonary function following exposure is evaluated by measurement of lung volumes, C0 diffusing capacity, expiratory flow rates and N2 washout. Pathologic changes are evaluated by light and electron microscopy, uptake of 3H-thymidine by epithelial cells of the bronchiolar and alveolar regions, permeability of respiratory epithelium to horseradish peroxidase, increase in plasma angiotensin converting enzyme and examination of lung lavage fluid for cell population and content of lytic enzymes. Characterized coals or spherocarb impregnated with Fe or Cu are burned in a laminar-flow furnace permitting control of temperature and 02 partial pressure. Special emphasis is placed on determination of H2S04, both as free H2S04 and as a layer on ultrafine aerosols, and on how H2S04 formation relates to composition of coal and to combustion conditions.